The neurologist’s latest investigations of the mind explore the mystery of hallucinations – including his own

He goes on to talk about why he ended his own experiments with hallucinogens.

“The last one was in February of ’67,” he recalls. “But I felt somehow tilted into the mode of wonder and creativity, which I’d known when I was much younger. While there have been dead periods, that [mode of wonder] has been with me ever since.